How to optimize indexes in MariaDB and what are the index types and optimization strategies?

Index optimization in MariaDB is crucial for improving database performance. Here are the main optimization strategies:

1. Index Type Selection

B-Tree Index (Default):

• Suitable for equality and range queries
• Supports sorting and grouping operations
• Use cases: Most query scenarios

Hash Index:

• Only supports equality queries
• Extremely fast query speed
• Use cases: Exact match queries

Full-Text Index:

• Supports text search
• Use cases: Content search, article retrieval

Spatial Index:

• Supports geospatial data
• Use cases: Geographic location queries

2. Index Design Principles

1. Choose Appropriate Columns:

   • Columns in WHERE, JOIN, ORDER BY, GROUP BY clauses
   • High selectivity columns (many unique values)
   • Avoid creating indexes on low selectivity columns

2. Composite Index Order:

   • Place the most frequently used columns first
   • Follow the leftmost prefix principle
   • Consider column selectivity

3. Avoid Over-Indexing:

   • Indexes increase write overhead
   • Occupy additional storage space
   • Regularly clean up unused indexes

3. Query Optimization Techniques

sql
-- Use EXPLAIN to analyze queries
EXPLAIN SELECT * FROM users WHERE name = 'John';

-- Create appropriate indexes
CREATE INDEX idx_name ON users(name);
CREATE INDEX idx_name_age ON users(name, age);

-- Use covering indexes to avoid table lookups
SELECT id, name FROM users WHERE name = 'John';

-- Avoid using functions on indexed columns
-- Not recommended: WHERE YEAR(created_at) = 2024
-- Recommended: WHERE created_at >= '2024-01-01' AND created_at < '2025-01-01'

4. Index Maintenance

sql
-- Analyze index usage
SELECT * FROM information_schema.statistics 
WHERE table_schema = 'your_database';

-- Rebuild indexes
ALTER TABLE users ENGINE=InnoDB;

-- Drop unused indexes
DROP INDEX idx_unused ON users;

5. Performance Monitoring

sql
-- View index statistics
SHOW INDEX FROM users;

-- Analyze table
ANALYZE TABLE users;

-- Optimize table
OPTIMIZE TABLE users;

Through proper index design and maintenance, you can significantly improve MariaDB's query performance.